I was able to locate which of the 10 coil packs had gone bad in my v10 yesterday with a code reader from Advance Auto. It threw a code that said coil pack B had failed. After deciding that I didn't have the time or arm lenght to remove one coil pack at at time to determine which one was actuall bad I assumed that the front passenger coil was A and that the other packs on that side would have to be B,C,D and E if I was correct. I pulled the coil pack on the rear of the motor since it was easiest to reach and then started the motor and then shut it down. Read the codes and it now indicated two failed coil packs, B and E. I replugged the rear coil and started the motor, pulled the codes and it now only shows B as the failed coil pack. 10 minutes later I replaced coil pack B and the beast was running smooth as silk. Just thought I would pass this on since I couldn't find any reference to identifying coil packs on this forum other than pulling them one at a time and noticing how the motor performed. Have a great day.